Embedded tube heat exchanger



May 26, 1970 G. B. SINGH EMBEDDED TUBE HEAT EXCHANGER Filed Aug. 18,1967 INVENTOR GURU B. SINGH WM Ill ll/f ATTORNEY 3,513,908 EMBEDDED TUBEHEAT EXCHANGER Guru B. Singh, 6329 31st Ave., Kenosha, Wis. 53140 FiledAug. 18, 1967, Ser. No. 661,572

Int. Cl. FlSd 1/02; F28f 13/06 US. Cl. 165-109 1 Claim ABSTRACT OF THEDISCLOSURE A device for transferring heat between a portion of theexterior walls and adjacent conductor surfaces of a first circuitenclosed within a second circuit. Increased contact of fluid in thesecond circuit with the exterior walls and adjacent conductor surfacesof said first circuit results from surrounding the enclosed portion ofthe first circuit with a porous substance consisting of a layer offinely divided metallic particles. To overcome the tendency of fluidthus restricted to establish fixed passages when flowing between suchmetallic particles, a core having helically arranged radial ribs isinserted to interrupt the laminar fluid flow just prior to entry of suchfluid into such particles.

BACKGROUND OF THE INVENTION Field of the invention This inventionpertains to the art of transferring heat energy from one fluid substanceto another by passing the first such fluid substance through the second.

Description of prior art The art of positioning one section of a firstconduit within a second conduit such that fluid flowing through thefirst will gain or lose heat from or to the second, is well known. It isalso well known that some means for transforming laminar flow throughthe second circuit to a turbulent flow substantially increases the heattransfer efliciency of the exchanger. Such increase in efliciency isattributable to the increased number of particles of a second circuitfluid which are brought into proximity with the walls of the firstcircuit. Use of a granular substance having a great number of granulesand corresponding interstices to surround the first circuit createsmultiple avenues through which second circuit fluid flows, therebybreaking up laminar flow. However, the improvement in efficiency of heatexchange resulting from introduction of such multiple avenues is limitedinasmuch as the newly created multiple avenues become fixed and maximumturbulence is not produced. It is apparent that the need is for meansfor approaching completely random motion of the fluid through theinterstices in order that maximum contact between units of secondcircuit fluid and the walls of the first circuit and conductor surfacesadjacent thereto, will result.

SUMMARY OF THE INVENTION The foregoing background illustrates the stateof the heat exchanger art at the time of the applicants instantinvention. Through such invention means is provided for directing fluidthrough a series of small passages in a medium surrounding a completelyseparate fluid circuit, such that the passages followed by such fluidare con stantly changing in a random pattern producing maximumturbulence in the fluid flow. The production of maximum turbulence insuch flow constitutes the principal object of this invention. A furtherobject of this invention is to provide a helically curved obstruction inthe path of fluid flow in one of the fluid circuits of a heat exchangersuch that the curvature of such obstruc- United States Patent 3,513,908Patented May 26, 1970 "ice tion will provide maximum turbulence withouta substantial pressure drop within the circuit.

In the attached drawings and following description, the best modepresently contemplated for carrying out the invention is set forth. Themanner and process of making and using the invention is described belowin such full, clear and concise and exact terms as to enable any personskilled in the art to which it pertains, or with which it is most nearlyconnected, to make and use the invention. It should be emphasized,however, that the subject matter regarded as the invention is notlimited solely to the here described embodiment of it, but ratherincludes everything falling within the claims set forth at theconclusion of this specification.

FIG. 1 is a cross sectional view of the heat exchanger incorporating aform of the invention.

FIG. 2 is a cross sectional view taken along the line 22 of FIG. 1.

FIG. 3 is a perspective view of the helically ribbed core removed fromthe heat exchanger.

Referring now to the drawings in detail, FIG. 1 shows a first fluidcircuit 16 having inlet 5, continuous coils 4, and outlet 6. FIG. 1 alsoshows a second circuit 17 comprising inlet 8, outlet 9, an innercylinder 15 with solid end walls 10 (through which inlet 8 opens) and 11and porous side walls 3 in which the coils of circuit 16 are located;and an outer cylinder 14 with solid side walls 1 and solid ends 13(through which inlet 8 extends into cylinder 15) and 12 (through whichoutlet 9 extends from cylinder 14).

Inside cylinder 15 is ribbed core 18 consisting of longitudinal shaft 19from which radially project longitudinal ribs 7. Each such rib is formedas a helix longitudinally of shaft 19, preferably having 10 of curvaturefor each inch of shaft length. As fluid in closed fluid circuit 17 enterinlet 8, laminar flow is altered by the effect of ribs 7 and shaft 19such that turbulence is created prior to entry of the fluid into sidewall 3 of cylinder 15. Side wall 3 is composed of a porous substance,preferably sintered metallic particles of nickel plated copper having ahigh resistance to corrosion. Turbulent flow of fluid from ribs 7 entersside wall 3 in random directions. This results in a continuouspenetration of said fluid into substantially all of the spaces betweenparticles in wall 3 enabling the conducting properties of said wall 3 toact in exchanging heat with the passing fluid to a maximum extent.

After penetration of the pores in wall 3, fluid in circuit 17 passesinto space 2 and leaves cylinder 14 through outlet 9.

It will be observed from the foregoing description that this heatexchanger is readily adaptable for manufacture with varying circuitsproximate to each other, and with alternate devices for positioning ribswithin such circuits, or at least one such circuit, to produce thenecessary turbulence. Likewise, use of any porous substances which havesuitable properties of heat conduction may be substituted for sinteredmetallic particles described above. While I have illustrated a preferredembodiment of the invention, many other modifications may be madewithout departing from its spirit.

Accordingly, I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all embodimentswhich are reasonably covered by the appended claim.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States, is:

1. In a heat exchanger, the combination of:

a first closed circuit having tubes wound in the form of a coil withexposed surfaces embedded within a layer of finely divided metallicsintered nickel plated copper particles forming the wall of a cylinderhaving an opening for introduction of a fluid,

a first fluid for flow within said first closed circuit,

a second closed circuit entirely enclosing the exposed surfaces of saidcoil and said cylinder wall such that interstices in said cylinder wallcomprise the sole communication between two lateral sections of saidsecond closed circuit,

a second fluid -for flow within said second closed circuit,

means for directing the entire fluid flow in said second circuit throughsaid cylinder wall, and

deflector means in said second circuit within said cylinder and adjacentthe exposed surfaces of said cylinder wall comprising a core withhelical ribs fixed thereto arranged along its longitudinal axis in theform of a spiral in which each such rib has a curvature of 10 for eachinch of length.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 7/ 1924 GreatBritain. 6/ 1938 Great Britain. 7/ 1966 Great Britain.

ROBERT A. OLEARY, Primary Examiner A. W. DAVIS, JR., Assistant ExaminerUS. Cl. X.R.

